In general, the optical access network technology is widely used due to the characteristic of connecting a service provider to each subscriber through optical infrastructure and improving service quality.
FIG. 1 is a diagram schematically illustrating a conventional optical access network. As shown in FIG. 1, the optical access network includes a single service provider connected to a plurality of subscribers through a single optical infrastructure. Accordingly, in order for the subscriber to receive a service from another service provider, a new optical infrastructure needs to be built between the different service provider and the subscriber. In this case, the previous optical infrastructure which has been connected to the subscriber for the previous service provider is not available for use.
If the previous optical infrastructure is configured such that access of the other service provider is easily made instead of building a new optical infrastructure, the service provider can reduce the cost of building an optical infrastructure. In addition, the efficiency in use of the previous optical infrastructure is enhanced, thereby providing a user with cost effective services.
As an example of using the previous optical infrastructure as it is, a technology of using a wavelength division multiplexed signal light and a wavelength tunable light source has been suggested. This technology prevents implementation complexity of sending a supervisory control signal in addition to a signal wavelength to each subscriber and assigning wavelengths for transmission and reception.
That is, this technology provides an intelligent communication method in which each service provider apparatus and subscriber selects a signal wavelength without using a supervisory control signal. To this end, the service provider apparatus and subscriber each have a wavelength tunable laser transmitter and a wavelength tunable receiver equipped with a wavelength tunable filter. The service provider apparatus controls the signal wavelength, and an optical link is configured by an optical splitter.
The benefit of this technology is that an optical splitter is used and each service provider apparatus and subscriber selects wavelengths in an intelligent manner. However, this technology has a limitation in accessing of a plurality of service providers to the optical infrastructure in that respective service provider apparatuses need to share a single wavelength control circuit, thereby causing a difficulty in accessing the optical infrastructure.
That is, the need for another system enabling the service provider to share the optical infrastructure arises.
As another example of using the previous optical infrastructure as it is, an open optical access service model technique using a wavelength division multiplexing (WDM)-passive optical network (PON) has been suggested. This technique allows a service provider to send a signal desired by the service provider by including an Optical Cross Connect (OXC) in a central node. However, this technique is implemented by use of a wavelength division multiplexer provided in a remote node, so the wavelength assigned to each subscriber is limited to a signal wavelength, causing a difficulty in that each subscriber receives services from a plurality of service providers.
This has caused the need for a technique of reducing an additional system for managing each service provider system from an open optical access network and removing the limitation of wavelengths assigned to each subscriber.